Even if the tale isn’t ‘truth’ it’s still a decent warning regarding how scammers will use discomfort and threat to bully money out of you.
Payment for expensive items is always tricky and there is no 100% safe method for both parties.
Anything I can think of would be long winded and expensive and immediately falls apart if both parties are not in the same place.
The only sane thing to do is never sell your watches.